<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JQuery</title>
    <!-- 引入外部jquery文件 -->
    <script src="js/jquery-1.8.3.js"></script>
    <script>
        // $(document).ready() 当网页完全加载完成的时候执行
        $(document).ready(function() {
            alert("你好");
        });
    </script>

</head>

<body>
</body>

</html>